This invention relates to an absorbent article, and more particularly to an absorbent article having an improved construction. This invention also relates to a process of making such absorbent articles.
Numerous absorbent articles, such as disposable diapers and sanitary napkins, have been proposed for absorbing and retaining body fluids. Usually, the articles are constructed with an absorbent pad having a relatively large volume of pad material in order to provide the necessary absorbency and fluid holding capacity for the articles. As a result, such articles are undesirably bulky. For instance, disposable diapers are commonly made from a fluid impervious backing sheet, a fluid pervious cover sheet, and an absorbent pad, such as comminuted wood pulp known in the art as wood fluff, interposed between the backing and cover sheets. The pads of such conventional diapers are relatively bulky, particularly in the crotch region, resulting in a poor fit and minimal comfort to the wearer.
More recently, it has been proposed to use highly absorbent materials, such as hydrocolloid polymers, in the pads. In theory, the hydrocolloid materials permit a reduction in pad bulk while increasing desirable absorbent and fluid holding characteristic of the pads, since such materials are capable of absorbing and retaining many times their weight in liquids. However, in practice, the use of such materials in absorbent articles has been limited due to numerous difficulties brought forth by the materials themselves.
It is preferred that the hydrocolloid material be utilized in a particulate form, such as granules or flakes, in order to provide a greater exposed surface area for increased absorbency. However, it has been found that when placed in the pad, the particles migrate in the pads before the article has been used. Such particle migration may take place during packaging, storage, transportation, or other handling of the articles, resulting in movement of the particles from their initial location to remote parts of the pad where they are less effective.
In addition, when wetted, the hydrocolloid materials swell and become gelatinous. As a result, the materials migrate further in the pad when wetted, and cause the pad to become unstable. Thus, it has been found that the wetted materials cause the pad to shift, ball, split and shred during use of the articles.
Still more recently, an absorbent article comprising an absorbent pad assembly having an absorbent pad and pockets for retaining a hydrocolloid material in association with the pad is taught in U.S. Pat. No. 4,055,180 to Karami. According to this patent, two fluid impervious retaining sheets are attached to areas to define pockets in which the absorbent material is stored. Openings are provided in one of the retaining sheets to permit passage of the fluids into the pockets. Since the openings must be formed in the retaining sheet and adhesives are used to bond the retaining sheets together, such an absorbent article is not economically advantageous.